It is well known that gelatin has been used, inter alia, in a wide range of food products, such as gelatin containing courses, compressed meats, pastries, and the like. It is also well known that gelatin has been used to deliver pharmaceuticals in capsule form for more than one hundred years. It has many useful physical and chemical properties, which support this broad range of utility.
The primary sources of gelatin are from bovine animals and pigs. The source of gelatin can be a problem for potential areas of use or for particular consumers. Large groups of people around the world cannot ingest any products derived from these animals, because of religious beliefs or because of dietary requirements and preferences. Additionally, as there has recently been at least one alleged instance of cross-species contamination from cattle to humans (at least one alleged instance with bovine spongiform encephalopathy, BSE, or “Mad Cow Disease” in the United Kingdom), the use of uncontrolled by-products from animals has lost some level of commercial acceptance. It has become apparent that replacement compositions for gelatin, which are not derived from animals, are desirable.
For example, U.S. Pat. No. 5,942,266 ('266 patent) sets forth one method for capsule formation using alginates which comprises contacting liquid drops of a composition of an aqueous solution of a water-soluble macromolecular substance (such as guar gum) at least a portion of which is marmelo mucilage, an oleaginous substance (such as animal or vegetable oil), a water-soluble polyvalent metal salt (such as calcium chloride), with an aqueous solution of a water-soluble salt of an alginic acid, thereby forming a water-insoluble film of alginic acid salt on the outer surface of the liquid drop. As reported in the '266 patent, the amount of oleaginous substance that is encapsulated can be in the range of 10% to 95% by weight of the liquid drop. In order to encapsulate such a relatively large amount of oleaginous substance (preferably 30-85% by weight of the liquid drop), the composition of the liquid drop in the '266 patent is very complex; requiring the presence of exacting amounts of macromolecular substance, oleaginous material, polyvalent metal and other salts; and the essential requirement of marmelo mucilage. The oil-entrapment with the use of marmelo mucilage led to formulations where separation began after only 30 minutes, confer column 6, lines 27-30.
JP patent application no. 59166916 describes enteric soft capsules obtained by dual nozzles techniques. These techniques are limited to the provision of spherical capsules. Another frequent problem with capsules prepared by these techniques is capsules with walls of uneven thickness, due to density differences of the different phases during preparation.
JP 6055060 and JP 6079165 concern seamless coating film capsules containing surfactant and detergent preparation obtained by the use of multiple nozzles technique.
Thus, it can be seen that an improved, simpler method is needed for preparing stable robust seamless capsules comprising relatively large amounts of active materials.
Other references such as U.S. Pat. No. 4,702,921 disclose the preparation of capsules containing alginate gel membranes, but appear to use an amount of water that makes the capsules difficult to dry.
The present inventors have overcome the problems associated with the prior art wherein the capsules contain too much water.
It has now been found in accordance with the present invention that emulsions comprised of relatively large amounts of an active material, such as an oil, or added other component, can be prepared that offer an alternative to complex combinations of active material, water, and a plurality of other components. Accordingly, the objects of the present invention include: 1) a method of preparing seamless capsules of high stability, using water emulsions containing relatively large amounts of oils, 2) a simple method of preparing seamless capsules of high stability that encapsulate the aforementioned water emulsions of oils with other solid, or liquid or gaseous components added, in a polysaccharide gel membrane, and 3) optionally, a method of drying and coating the polysaccharide capsules of emulsion for a subsequent use. Furthermore the shape of the capsules of the present invention can be determined prior to the preparation, and the capsules of spherical, oval, oblong or cylindrical shape prepared according to the methods of the present invention have an uniform wall thickness. The capsules of the present invention have an excellent integrity and storage stability over a prolonged period of time.